(1) Field of the Invention
The present invention relates to building glass materials and, in particular, to glass bricks or hollow glass blocks which are hollow bodies of glass used in building walls.
(2) Description of the Prior Art
Those glass bricks or hollow glass blocks are known as building wall materials in the prior art, as described in, for example, BRITISH STANDARD 1207:1961 (Reference 1). That is, the glass bricks are used for walls separating the inside and the outside of buildings as lighting walls, and are also used for partitions in rooms.
Those glass bricks are conventionally formed of light transparent glass such as soda-lime-silica glass. Each of the glass bricks has an inner hollow space and is formed in a generally rectangular hollow body. Further, the glass brick is usually formed with a rugged pattern in an inner surface of the hollow body so as to diffuse or scatter a light ray transmitting from one side of the glass brick to the opposite side through the glass brick in various directions. As a result, an inside room separated from the outside by the glass brick wall is generally uniformly lighted by an external light transmitted through and diffused or scattered by the glass bricks.
However, when the glass brick wall is exposed to direct sunlight, each of bricks often glares or glitters at the rugged pattern undesirably and makes a dazzle light for persons in the room. Furthermore, when a light incident angle to the brick increases, the refraction due to the rugged pattern is reduced so that the light scatter or diffusibility is not effectively performed.